From Manufacturer
The Warm Direct Box Passive is designed for use with electric instruments with active pickups such as basses and guitars as well as line-level instruments. The design is based around renowned electrical components such as the custom-wound CineMag transformer at its core. With its rugged extruded aluminum enclosure, its rugged metal switches, and Pad knob it will provide a warm tone over long cable runs as well as durability on the road.
On the front of the unit, you'll find a 1/4" input and an Amp/Instrument toggle switch. This toggle switch selects between line-level and instrument-level settings so you can use the box with either your high-impedance instruments (guitars and such) or line-level keyboards. A polarity switch and ground-lift switch are on hand, and you'll also note the 1/4" thru-put, which mirrors the input and lets you pass unaffected signal to destinations such as stage amplifiers. Now you can feed your amp on stage and send mic-level signal to the house mixer at the same time.
On the rear, you'll see an XLR output and a variable pad knob that lets you attenuate your signal between -3 and -30 dB, giving you another useful gain-stage. You can switch the pad out entirely with the Engage toggle switch.
This is the passive model, which is better suited for balancing the signal of instruments with active electronics such as electric guitars geared towards heavy metal and many electric basses. However, the DI box sports a frequency range of 20 Hz to 70 kHz at ±0.5 dB, so it can still handle passive instruments with a range that eclipses many other DI boxes. Passive DI boxes do not require power to operate.